The invention relates to a winding shaft for a roller blind system with a main body for holding a rolled up planar structure that can be unwound from the winding shaft, where the main body takes the form of a partial cone around a winding shaft axis.
Generic winding shafts are known to the pri- or art. They are used for roller blind systems in motor vehicles where it is desirable for a planar structure stowed on the winding shaft not to be unrolled from the winding shaft in a straight line, but to follow a slightly curved path. The outsides of these generic winding shafts have the form of a partial cone, where opening angles of less than 10° are usually employed.
The manufacture of generic winding shafts has until now represented a problem with no satisfactory solution. The effort required to produce a conically widened plastic body is comparatively high, and its stability is not satisfactory. For this reason, use is instead most often made of cylindrical base bodies onto which a planar structure is glued and which, due to an approximately triangular form of the planar structure when glued, gives the winding shaft an approximately conical form. The use of hollow cylindrical shafts as a base body, onto the surface of which plastic is sprayed in order to achieve the shape of a cone or partial cone, is also known.